Many types of mobile apparatus such as access platforms with an elevating work platform, cranes etc rely on stabilizers (also known as outriggers) to provide and maintain stability during lifting operations, such as raising of a work platform. Known arrangements use stabilizers that are either manually set up or that rely on powered actuation, e.g. by hydraulic cylinders or linear actuators. In some situations, it is required to have a failsafe interlock system that prevents lifting operations unless the stabilizers are correctly deployed. In known arrangements, this is achieved by use of electrical sensors or switches which have a built in safely circuit or rely on positive mechanical action of the controlling contacts, or by use of a hydraulic shut off valve that is activated by a cam action as the stabilizer deploys.
The known arrangements are complex and costly, and the present invention aims to provide a simpler alternative.